1. Field of the Invention
The present invention relates to a dry powder inhalation device for the inhalation of pharmaceutical or nutraceutical compounds including excipients in dry powder form. More particularly, it relates to a dry powder inhalation device having a toroidal chamber for uniform particle size delivery to a patient.
2. Description of Related Art
Pressurized metered dose inhalation devices (pMDI) are well-known for delivering drugs to patients by way of their lungs. pMDI's are comprised of a pressurized propellant canister with a metering valve housed in a molded actuator body with integral mouthpiece. This type of inhalation device presents drug delivery challenges to patients, requiring significant force to actuate with inhalation and timing coordination to effectively receive the drug. pMDI's containing suspended drug formulations also have to be shaken properly by the patient prior to actuating to receive an effective dose of the drug. These relatively complicated devices also require priming due to low drug content in initial doses and can require cleaning by the patient. In some devices, an additional spacer apparatus is prescribed along with the pMDI to compensate for the timing coordination issue although the downside for the patient has to pay for, clean, store and transport the bulky spacer apparatus. While many patients are experienced operating pMDI's or pMDI's with spacers, new patients have to go through the relatively significant learning curve to operate these devices properly.
Dry powder inhalation devices (DPI) are also well-known for delivering powderized drug to the lungs. DPI technologies are either active involving external energy to break-up and aerosolize particles or, passive utilizing the patient's inspiratory energy to entrain and deliver the powder to the lungs. Some DPI technologies integrate electronics while others are fully mechanical. The powder drug storage formats are normally reservoir, individually pre-metered doses or capsule based systems. Drug formulations delivered by these devices involve in some devices innovative engineered drug particles but in most devices deliver a conventional blend of sized active pharmaceutical ingredient(s) (API) plus sized lactose monohydrate used as a bulking agent to aid in the powder filling process and as a carrier particles to aid in delivery of the active pharmaceutical ingredient(s) to the patient. These API-lactose monohydrate blends among others require a means to break-up aggregates formed by attractive forces holding them together.
Nebulizers are well known for delivering drugs in solution to the lung. While these drug delivery systems are effective for patients lacking the inhalation capability or coordination to operate some hand held inhalation devices, they are large equipment requiring an electrical power source, cleaning and maintenance. Administration of nebulizer drugs involves significant time and effort; transporting, setting up electrically, loading individual nebules, assembling the patient interface mouthpiece and delivering doses to the patient.
Inhalation therapies currently being administered in institutional settings are either multidose pMDI, multi-dose DPI's or nebulizer all of which demand substantial attention of health care providers to administer. All current options require substantial effort from the nurse or respiratory therapist to administer, track doses and maintain to meet the needs of the patient. Current options available in the institutional setting require the in-house pharmacy to dispense multi-dose devices that in most devices contain an inappropriate number of doses relative to the patient's stay and disposal of unused doses when patients are released. Additionally, multi-dose inhalation devices requiring repeated handling over multiple days in these settings increase the chance of viral and bacterial transmission from person to device to person within the environment. Thus, the complexities associated with the currently available inhalation devices result in considerable cost impact to the healthcare system.
Unit dose inhalation devices taught in the art typically involve relatively complicated delivery systems that are relatively heavy, bulky, and costly to manufacture. In addition, most passive dry powder inhalation devices suffer from flow rate dependence issues in which drug delivery may vary from low to high flow rates. Some devices require substantially low pressure to be generated by the patient to operate properly and receive the drug effectively. Generating significant low pressure can be difficult to achieve especially for young and elderly patients. In many cases, the inhalation device technologically taught in the art does not provide adequate feedback features to inform the patient or health care provider if, 1) inhalation device is activated and ready for use, 2) powderized drug is available for inhalation, 3) powderized drug has been delivered, or 4), and Inhalation device has been used and is ready to be disposed of.
In US 2012/0132204 (Lucking, et al.), there is described an inhalation device with a simple flow-through powderized drug storage chamber. In this device, air flows through the air gap present after the activation strip is removed from the rear of the inhalation device. Air flows in a non-specific flow pattern to entrain the powderized drug and deliver it straight through the inhalation device and to the patient. The amount of air and resistance of air flow entering the drug storage chamber is susceptible to sink and flatness irregularities in the molded or formed components and compressive forces applied by the patient's hand while operating the inhalation device. Powderized drug is not cleared from the powder storage chamber with a controlled flow pattern leaving the potential for flow dead zones, powder entrapment and drug delivery performance variability especially across a range of flow rates from low to high, 30 L/min to 90 L/min for example. There is no specifically designed means for deaggregating powderized drug besides the flow transition from the powder storage chamber to the fluidly connected channel.
A second embodiment is described with a circulating spherical bead powder dispersion chamber separate and downstream from the powder storage chamber. This embodiment involves more complication with moving beads acting as a mechanical means to grind, and break up powder aggregates as part of the dispersion process. The separate chambers and fluidly connected channel create relatively high surface area for powderized drug including the finer respirable particles to attach and fail to emit from the inhalation device. The circulating beads are driven by air flow generated by the patient which can vary dramatically having an effect on performance with such inhalation driven mechanisms. In addition, these types of mechanisms require substantial low pressure to be generated by the patient to actuate.
In U.S. Pat. No. 6,286,507 (Jahnsson, et al.), there is described an inhalation device with a simple powder storage chamber separate from the powder deaggregation means which is located in the fluidly connected channel. Having these two design elements separate creates significant device-drug contact surface area and the potential for substantial drug hold-up due to finer more respirable particles with less mass and momentum attaching to the contact surfaces. In addition, the activation strip is removed from the rear of the device, not providing mouthpiece obstruction and obvious indication to the patient that the device needs to be activated.